Diabetes affects between 6.5 and 13 million Americans and is associated with an expenditure of over $44 billion in direct health care costs per year. Prevalence rates for Latinos, America's fastest growing minority, are approximately twice that of European-Americans (EAs). Depression occurs as a comorbid condition in 23% of EAs with diabetes, but the rate of depression among Latinos with diabetes is almost 30%. Depression is associated with decreased self-management behavior, poor metabolic control, and increased risk for complications. Explanatory models, based almost exclusively on cross-sectional research, suggest that depression has both direct and indirect effects on metabolic control through self-management. Disease severity, impairment, complications, life stress, personal resources, access to care, and social support also affect these relationships. Given the pervasiveness of depressive affect, the variability in self-management among EA and Latino patients with diabetes, and the increased behavioral and biological risk that depression poses for these patients, longitudinal studies with implications for intervention are needed to describe the forms that depression and self-management can take in these patients over time. The proposed 4-wave, 24-month longitudinal project seek to: (1) describe the variation, and sub group patterning of depression and self-management over time in EA and Latino patients with type 2 diabetes; (2) identify the linkages among depression, self-management, and metabolic control, over time, along with factors that moderate these linkages; and (3) determine variations in these relationships based on patient ethnicity (EAs, Latinos). The proposed longitudinal research has major implications for intervention: it will provide a more complete description of the natural course of the full range of major and minor depression and self-management over time; it will identify sub group variations that may warrant specific interventions; it will identify at what point along the continuum of depression linkages with disease self-management and metabolic control become evident; and it will highlight differences in these relationships based on patient ethnicity.